1. Field of the Invention
The present invention relates in general to an automotive air conditioning system, and more particularly to a heater/cooler unit of the system, which is usually mounted under an instrument panel of the vehicle. More specifically, the present invention is concerned with a heater/cooler unit which is compact in size.
2. Description of the Prior Art
In general, a heater/cooler unit of an automotive air conditioning system comprises three major parts, which are an air intake part for selectively taking in outside air and/or inside air, a cooler part for cooling the air from the air intake part and a heater part for heating the air from the cooler part. In operation, the air flowing from the air intake part is forced to make a heat exchange with the cooler and heater parts and thus conditioned. The heater/cooler unit is formed at a downstream portion thereof with a plurality of air outlet openings from which the conditioned air is led to various given areas of a passenger room through respective ducts.
Hitherto, in view of the tendency of downsizing the vehicles, various attempts have been made for reducing the size of the heater/cooler unit, one of which is shown in Japanese Utility Model First Provisional Publication 57-202311.
For clarifying the task of the present invention, a heater/cooler unit disclosed by the Publication will be outlined with reference to FIG. 7 of the accompanying drawings.
As shown in the drawing, the heater/cooler unit comprises an integral casing 1 in which a generally U-shaped air flow passage xe2x80x9cPxe2x80x9d is defined by curved walls. At an upstream portion of the passage xe2x80x9cPxe2x80x9d, there is installed an electric fan xe2x80x9cfxe2x80x9d for taking in outside and/or inside air. An outside air inlet opening xe2x80x9c2bxe2x80x9d and an inside air inlet opening xe2x80x9c2axe2x80x9d are exposed to the upstream portion of the passage xe2x80x9cPxe2x80x9d with an air intake door 9 arranged therebetween. At a portion just upstream of the lowermost portion of the U-shaped passage xe2x80x9cPxe2x80x9d, there is installed an evaporator 3 by which the air from the electric fan xe2x80x9cfxe2x80x9d is cooled. As shown, a downstream portion of the U-shaped passage xe2x80x9cPxe2x80x9d with respect to the lowermost portion of the same is enlarged and has a heater core 6 installed therein. At a terminal end portion of the passage xe2x80x9cPxe2x80x9d, there is defined an air mix chamber 7. Due to presence of the heater core 5, the enlarged downstream portion of the passage xe2x80x9cPxe2x80x9d defines two shorter air flow passages 6a and 6b, one being an air heating passage 6a including the heater core 5 and the other being a bypass passage 6b bypassing the heater core 5. As shown, these two shorter passages 6a and 6b have downstream ends merged with the air mix chamber 7. An air mix door 4 is arranged to control the rate between the amount of air directed to the passage 6a and the amount of air directed to the other passage 6b. A ventilation opening 8v and a foot space opening 8f are exposed to the air mix chamber 7. That is, in operation, conditioned air in the air mix chamber 7 is led to given areas of the passenger room through the ventilation and foot space openings 8v and 8f respectively.
Due to usage of the generally U-shaped air flow passage xe2x80x9cPxe2x80x9d, the cooler/heater unit can be fairly reduced in size. However, as is understood from the drawing, the arrangement of placing the air flow passage xe2x80x9cPxe2x80x9d between the evaporator 3 and the heater core 5 has failed to obtain a satisfied compactness of the cooler/heater unit. In fact, due to such arrangement, the thickness xe2x80x9cTxe2x80x9d of the unit increases by a non-negligible degree.
In order to solve this drawback, a measure may be thought out in which the evaporator 3 and the heater core 5 are vertically aligned in the upstream part of the U-shaped air flow passage xe2x80x9cPxe2x80x9d for reduction of the thickness xe2x80x9cTxe2x80x9d. However, this measure tends to induce another drawback wherein due to inevitable size-difference of the evaporator 3 and the heater core 5, the passage containing these devices 3 and 5 is forced to have a complicated structure. Usually, the evaporator 3 is larger than the heater core 5. As is known, providing the cooler/heater unit with such a complicated structure causes a creation of useless space or dead space around the unit upon assembly in the vehicle.
It is therefore an object of the present invention to provide a compact heater/cooler unit of an automotive air conditioning system, which is free of the above-mentioned drawbacks.
According to the present invention, there is provided a heater/cooler unit which is produced compact in size by effectively using the spaces which would be inevitably produced when the unit contains an evaporator and a heater core which are different in size.
According to a first aspect of the present invention, there is provided a heater/cooler unit of an automotive air conditioning system. The unit comprises a casing having air inlet and outlet openings which are connected through an air flow passage defined by the casing, the casing including an enlarged portion and a reduced portion by which an enlarged part and a reduced part of the air flow passage are defined respectively, the casing thus having a concave contour defined by the reduced portion thereof; an evaporator installed in the enlarged part of the air flow passage; a heater unit which is smaller in size than the evaporator, the heater unit being installed in the reduced part of the air flow passage; and at least one duct snugly extending along the concave contour of the casing, the duct having one end connected to a downstream portion of the air flow passage.
According to a second aspect of the present invention, there is provided a heater/cooler unit of an automotive air conditioning system. The unit comprises a casing including a body portion and a head portion which are integrally molded, the body portion including an enlarged lower part and a reduced upper part which are connected through a smoothly curved intermediate part, the casing thus forming at both sides of the reduced upper part concave outer surface portions thereof, the head portion defining therein an air mix chamber which is communicated with the interior of the reduced upper part; an evaporator installed in the enlarged lower part of the casing; a heater core which is smaller in size than the evaporator, the heater core being spacedly installed in the reduced upper part of the casing; an air mix door arranged between the evaporator and the heater core to control the rate between the amount of air which travels the heater core before reaching said air mix chamber and the amount of air which directly reaches the air mix chamber without traveling the heater core; and two ducts received on and extending along the concave outer surface portions of the casing respectively, each duct having one end connected to the air mix chamber.
According to a third aspect of the present invention, there is provided a heater/cooler unit of an automotive air conditioning system. The unit comprises a casing including a body portion and a head portion which are integrally molded, the body portion a center body part having a reversed T-shaped cross section and a thinner side body part attached to the center body part with a partition wall interposed therebetween, the center body part and the thinner side body part having respective upstream ends connected as well as respective downstream ends connected, the casing forming at both sides of the center body part concave outer surface portions thereof which extend along the thinner side body part, the head portion defining therein an air mix chamber which is communicated with both the downstream ends of the center body part and the thinner side body part; an evaporator installed in an enlarged lower part of the center body part of the body portion; a heater core which is smaller in size than the evaporator, the heater core being spacedly installed in a reduced upper part of the center body part; an air mix door arranged between the evaporator and the heater core to control the rate between the amount of air which travels the heater core before reaching the air mix chamber and the amount of air which directly reaches the air mix chamber without traveling the heater core; and two ducts received on and extending along the concave outer surface portions of the casing, each duct having one end connected to the air mix chamber.